Glow-discharge lamp



April 14, 1931. J. L. BAIRD 1,800,926

Patented Apr. 14, 1931 UNITED STATES PATENT OFFICE JOHN LOGIE BAIRD, OI LONDON, ENGLAND, .ASQIGNOR T0 TELEVISION LIMITEID, O]:

LONDON, ENGLAND, A BRITISH GOIMIPANY GLOW-DISGEARGE LAMI Application filed April 8, 1929, Serial N0. 353,635, am]. in Grea.t Britain J1Isi.y 4, 1928.

This invention concerns improvements in o1 relating to gloW-discharge lamps and the 1ike, such as neon tubes.

An object of the inventionis t0 provide a glovv-discharge lamp that will emit a coucentrated light, and that is applicable f01' use in connection with television 01' like apparatus.

A feature 0f the present invention is a glowdischarge lamp or the like (for example a neon tube) having an electrode in the form of a light-concentrating reflector, for example in the form of a concave or a partcylindrical reflector.

Conveniently a companion electrode of the lamp is situated in or approx'imately in the principal focus 0f said reflector, in which case this electrode is preferably ball-shaped if the reflector is concave in form and preferably rod-shaped i f the reflector is of a partcylindrical configuration, the longest dimension of the rod-shaped electrode being disposecl parallel or substantially parallel to the axis of the reflector.

T0 concentrate the li ht upon an eflective area of the lamp, the %ack of the reflector may be covered er coated with non-conducting material.

Two forms of lamp, in accorda1ice with the present invention, will now be described, by way of example, and illustrated in the accompanying diagrammatic drawings, in which Figure 1 shows one form of lamp;

Figure 2 shows another form of lamp, and

Figure 3 is a transverse section throu h the reflector-electrode of the lamps of F1gures 1 and 2, t0 illustrate the relation of one electrode to the o ther.

'1 the lamp shown in Figure 1, which will be considered as a neon tube, the p'ositive electrode 2 is a spherical, parabolic or other concave refiector in or about in the principal focus of which the ball-shaped negative electrode 4 is situated. Each of the electrodes is supported respectively by conductors 6, 8 electrically connected by leads 7 9 with insulated contact plates (not shown but of known kind) in the bottom of the holder 10 cf the lamp which, of course, includes the usua1 tube or container 11. The conductors 6, 8 are supported in the usual pinch 12 and are insulated above the pinch 12 by tubes '14, 16 of glass 01' other suitable nonconducting material.

In the lamp of Figure 2ywhich also will be regarded as a neon tube, the negative electrode 18 is a rod-shaped member extending substantially parallel with the axis of the partcylindrical positive electrode 20x and located in o1 approximately in the principal focus of the positive electrode; in other respects the larnp of Figure 2 is similar to that shown in Figure 1 except that additional supports 22, 24 fast in the pinch 12 are provided for the positive electrodte. In cross section the electrode 20 may for example, be spherical or parabolic in shape.

In Figure 3, the position of the negative electrode 4 or 18 in respec t to its companion reflector-electrode 2 01 20, is indicated at 26. From this figure it will be apparent that rays due t0 the glow on the electrode 4 or 18 fall upon the reflector-electrode from whicli they are reflected in an approximately parallel beam. v

T0 concentrate the glow upon the front or Conoave side 01. the reflector-electrode, the back of the electrode may be covered or coated with any suitable insulating material, for instance mica 01' micanite, which is indicated at 28 in Figure 3. This material may, for example, be secured to the electrode by a few metallic clips 30.

When used in connection with television apparatus o1 the like, the refiectonelectrode 2 01 20 may be as large as or larger than the viewing ape1ture through which at the receiving station the received image is seen.

I claim 1. In a gloW-discharge lamp, the combination With an electrode of part cylindrical form having a light reflecting con cave surface, of. a companion rod-shaped electrode having its longest dimension disposed parallel to the cylindrieal elements of the first named electrode and located substantially in the principal focus of the light reflecting surface thereof.

2. In a glow-discharge lamp, the combination with an electrode 'I part cylixidrical form having a light reflecting concave surface, of a companion rod-shaped electrode having its longest dimension disposed para11e1 to the eylindrical elements of the first named electrode and located substantially in the principal focus of the light reflecting surface thereof,the convex surface of said first named electrode being covered with a non-conducting inaterial.

In testimony Whereof'I aifix my signature.

JOHN LOGIE BAIRD. 

